In the present study, the effect of a helical coiled tape on the heat transfer characteristics in a tubular heat exchanger has been studied. Numerical analysis is carried out in a tubular heat exchanger with a helical coiled tape insert under laminar flow conditions. The heat transfer characteristics, like Nusselt number (Nu) and friction factor (f), have been determined. Numerical modeling is undertaken and validated using analytical results. To study the parametric variation, simulation is carried out for different width ratios (WR) and twist ratios (TRs). It is observed that Nu increases as the WR is increased and the TR is reduced. The thermohydraulic performance index (THPI) is measured and found to be higher for a combination of a higher WR and a higher TR. From the tested values, it is seen that for a combination of WR = 3 and TR = 1.25, the maximum THPI was observed. It is concluded that both the tape width and pitch will significantly influence the thermohydraulic characteristics in a tubular heat exchanger with a helical tape insert inserted.
Introducing passive devices in the form of inserts helps to increase the heat transfer characteristics in a circular pipe. In the present work, the feasibility of using two twisted tapes has been numerically studied under laminar flow conditions. Two twisted tapes with configurations of co‐swirl and counter‐swirl conditions were simulated for Re ranging from 1000 to 2500. Heat transfer characteristics like Nusselt number, friction factor, and thermohydraulic performance index (THPI) were investigated. Even the effect of spacing of the tubes inside the pipe was numerically studied. Results indicated that the insertion of two tapes will improve the performance of the circular tube compared with a single tape in terms of a higher Nu and higher THPI. It is observed that for the co‐swirl condition for a Reynolds number of 1000, Nu and THPI is 38% and 29% higher than using a single tape, whereas, for the counter‐swirl condition, they are 43% and 34% higher than that of the single tape condition. Also, it is revealed that counter swirl positioning of the tape with an L/D ratio 0.56 outperformed all other configurations with the highest THPI.
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